Two-stroke-cycle internal-combustion engine



May 10, 1927. 1,628,

C. S. H. SNOW TWO-STROKE CYCLE INTERNAL COMBUSTION ENGINE Filed Dec. 1.2. 1924 2 Sheets-Sheet l May 10, 1927.

C, S. H. SNOW TWO-STROKE CYCLE INTERNAL COMBUSTION ENGINE Z'Sheets-ShQQ 2 Fild Dec.

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GHARIES STEWART HASTINGS SNOW, OF CROYIDON, ENGLAND, ASSIGNOE TO N. I. C. E.

I LIMITED, OF LONDON, ENGLAND.

TWOfiTROKE-CYCLE INTERNAL-COMBUSTION ENGINE.

Application filed December 12, 1924,.Serial No. 755,50'2, and in Great Britain June 4, 1924.

This invention relates to improvements in two-stroke cycle internal combustion engines and has forits object to increase their efficiency.

Accordingto. one feature of this invention, the pistons are made hollow throughout and the charge is passed through them. Thus, they constitute reservoirs or extra space for the charge which is thereby enabled to be transferred at a low pressure with consequent elimination of detonation on transfer. Further advantages of the aforementioned hollow pistons are,that the temperature over the whole piston is reduced which enables a good piston fit to be ,secure'd, better vapourization of mixture to be obtained, reduces the liability of detonation due to piston head heat, "and reduces condensation of the charge to a minimum. According to another feature of this invention,'there is provided, special valve mechanism to control the charge passing to the cylinders as hereinafter described. A' third feature of this invention consists of a bypass or balancin passage to vary the transfer aiid'ijalso, if desired, to act as a throttle.

In order that this invention may be the more clearly understood and readily carried into sheet, I will proceed to describe. the

same with reference to the accompanying drawings which illustrate embodiments of this invention, and wherein- Figure l is a central vertical longitudinal section, partly in elevation, of a twin-cylinder two-stroke cycle internal combustion en-' gine constructed in accordancewith this invention. 1

Figure 2 is a central vertical section of valve mechanism for controlling the charge passing to the cylinders, constructed in .accordance with this invention, and

Figures 3 and 4 are similar views of modified constructions of the said valve mechanism.

Like reference letters indicate like parts throughout the drawings.

Referring to Figure 1 of the drawings, the cylinders are each of two diameters and they consist of pump portions (1, (1 respectivelyand working portions 17, 6 respectively. The pistons are likewise each of two diameters, and they consistof pump portions 0 and c fitted with rings 0 and a respectively, and working or head portions 0 and c fitted with rings 0 and 0' respectively. The pistons are made hollow so as to constitute reservoirs and they are also of the deflector-head type. Each piston is formed with inner walls 0" whereby a conduit is provided extending substantially from a port 0 at one side of the lower end of the piston, up to the top of the piston and down to a port 0 near the lower end of the other side of the piston. The pistons are, further, furnished with lubrication holes 0 which communicate at their inner ends, with the crank-case, while their outer ends lead into grooves c". i

The fuel-induction ports, shown at a and a lead into the pump cylinders a and a respectively.

2 is.tl1e transfer passage, which is common to both of the cylinders.

e, e are the exhaust ports of the cylinders b and b respectively. i

f shows the water 'acket, 7 being the inflow and f the out ow. The spark-plugs.

are shown at g. The usual compressionrelease taps (not shown) are intended to be fitted in the apertures it.

The crank-case is made in two similar parts 3' and j and they are cast from the same pattern, thereby simplifying and cheapening construction. The parts j and j are secured to one another by bolts 7 and to the cylinders by set-screws k. Z 15 an oil well which is secured, by means of set-screws or the like, to the crankcase. It is provided with upstanding ribs Z furnished with holes Z the holes permit of circulation of the oil, while the ribs prevent its undue movement in the well. Z is an opening into which. an oil-filter and breather pipe (not shown) are intended to be fitted, and Z, 2 are apertures to receive drainage cocks.

Dealing now. with the valve mechanism shown in Fi res 2, 3 and 4, this is intended to be applie to the rear of the cylinders'as they appear in Figure 1. It comprises a valve-chest m of which the middle portion is machined out to receive, inthe construction shown in Figure 2, cylindrical valves n and n which are connected together by a spindle 12 and in the construction shown in Figures 3 and 4, the liner m of which the ends are bevelled to form valve seatings for the valves n and n In Figure 3 the valve a is formed integrally with the spindle n which slides in afi'xed guide a, and the are n epemge eel Weir ecie ptei e0 Eegi ports M 111101 a? he the endie 03% the ca we MW 1E me step L c peeviciied with leek Me with we feelde] L reepecfiwely. In J m screwed cape ewed acljuet were 2 emi ShG WH, them being; fee $11 perpeee e1 enabling e]? the mime he in e e Eshccht heifers en 11. e meh es e eleyeci 1m ebeerh when. WM

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emeller cylinders 2. In a. tweetmke cycle mtemel. eemhee fzlon engme plumhty Mt cyh c eech eemprismg e pump pumice pecvidtee w eh m mixture inlet port and Working pumice e1 smeHer diameter them the pump end brce'iflefl also with e Wensfee pe me-=- Working; in seid c fli ewe, each e1: F JiScUllS being provided; me e eufims ielly EL, ehepecl pe ge peel h 01pm eme mm ice the pump peefixiem e1 L cm" mi cylinder", extending up ehe flee flee piston and hevimyg its ethee end 124 o *te regiseee with {he eeeeefier 1pc i; e the L0 pieten is eppecmimetch? wt the We e1 1m cempeeseion stroke. 3.. l'n ewe fizreeefer pm. e, pure "items and Werking piemee Wee M. J in the mid cyiimde "5; respec tively, en" Um elem :Ze, WfiHF-fi eif the Km pump cyheeeee the WM gpieeeee being; We

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cessed at their lower ends to accommodate the connecting rods, and having their remaining portions made hollow in substantially U-torm and completely out ofl from the crank case, the said hollow portion open-' ing out into oppositely disposed ports which of working cylinders in communication therewith and also connected together by a short transfer passa e, pump pistons and working pistons wor ring in the said cylinders respectively, mixture inlets in the walls of the pump cylinders, the said pistons being recessed at their lower ends to accommodate the connecting rods and having their re-- malning portions made hollow in substantially U-form and completely out ofi? from the crank case, the said hollowportion opening out into oppositely disposed ports which permit the compressed mixture to be transferred through the pistons and through the transfer passage into the adjacent working cylinder, a valve chest connecting the said mixture inlet ports together, and reciprocating valves in said valve chest to control the flow of mixture to the cylinders 5. In a two-stroke cycle internal combustion engine, a pair of pump cylinders, a .pair of working cylinders in communication therewith and also connected together by a short transfer passage, pump pistons and Working pistons working in the said cylinders respectively, mixture inlets being formed inthe walls of the pump cylinders, the said pistons being recessed at their lower ends to accommodate the connecting rods and having their remaining portions made hollow in substantially Udorm and completely cut ofi" from the crank case, the said hollow portion opening out in-tooppositely disposed ports which permit the compressed mixture to he transferred through the piston and through the transfer passage into the adjacent working cylinder, and a lay-pass connecting the cylinders together whereby the transfer of the mixture can be controlled and whereby also the engine can be throttled,

In testimony whereof I have signed my name to this specification.

CHARLES H, SNQW. 

